The present invention relates to methods of tightening and loosening of objects.
More particularly it relates to methods of tightening and loosening objects on rotary bases.
There are a variety of different bolting applications in the industry. While the majority consists of flanges and casings or a static base, there are also applications on rotors and the like with rotary bases. In applying torque to a nut connected with a bolt, which is to connect two parts with one another, it often occurs that on static applications the bolt turns along with the nut and on the rotary applications the base turns along with the nut. One usually applies a backup wrench to stop the bottom nut from turning, or in case of a blind bolt that threads into the bottom half of a shell to be assembled, one applies an alien key or the like to the top of the bolt to stop it from turning. On a rotary base, one also applies an alien key to the top of the bolt to stop it and the entire base from turning.
It is believed to be clear that the above mentioned approach requires the use of backup or holding wrenches and keys which is time consuming and does not comply with today""s stringent safety standards in the industry.
German patent no. 1,902,413 and European patent document EP 0 593 742 disclose solutions for stopping the bolt from turning by keeping an inner sleeve/washer assembly stationarily during tightening of an outer nut. While the solution proposed in German patent no. 1,902,413 utilizes a holding wrench to do so, the solution proposed in the European patent document EP 0593742 uses a single tool which applies a holding force to the inner sleeve/washer assembly and an active force to the nut. The solution proposed in the European patent document works well on a static base, however it does not work on the rotary base as the rotary base eliminates the bearing face friction on which this solution relies to keep the inner sleeve/washer assembly stationarily with a holding force equal to the turning force. This means that in order to apply the tool disclosed in the European patent document on a rotary base, an additional holding tool is necessary to keep the inner sleeve/washer assembly stationary during tightening.
The holding tools in both above specified documents have to abut against an adjacent stationary object, simply because the nut assembly is subject to drag friction, which makes the nut or the inner sleeve/washer assembly turn at will. The only difference between the two solutions is that in the solution disclosed in the German patent document the inner sleeve/washer assembly has to be stopped by holding a tool from turning in the direction of nut, while in the solution proposed in the European patent document the inner sleeve/washer assembly has to be stopped from turning in the opposite direction of the nut. As the drag friction is sporadic, neither a human being nor a tool could instantly react when in the German patent document the turning force increases or decreases as a result of the drag friction, or when in the European patent document the friction variation lets the inner sleeve-washer assembly turn instead of the nut. That is why both require holding tools so as to keep the inner/washer stationary.
Accordingly, it is an object of the present invention to provide a method of tightening and loosening an object on a rotary base, which avoids the disadvantages of the prior art.
More particularly it is an object of the present invention to provide a method of tightening and loosening an object on a rotary base, which allows to avoid the use of a separate holding tool.
In keeping with these objects and with others which will become apparent herein after, one feature of the present invention resides, briefly stated, in a method of tightening and loosening an object to a rotary base torsion-free, comprising the steps of providing a single power tool having a tool housing portion and a driving portion which are coaxial with one another and provide equal but opposite forces; connecting a bolt with the rotary base; connecting a first part which includes a sleeve/washer assembly to one of said portions to be turned by said one portion, which sleeve/washer assembly includes a sleeve with a thread cooperating with a thread of the bolt and a washer abutting against the object; connecting a second part to the other of said portions to be turned by said other portion, which second part includes a nut having a thread cooperating with another thread of the first part; turning the first part by said one portion so that the first part, the bolt and the rotary base turn together while the second part remains free of rotation to urge the bolt to move in a desired axial direction to tighten or loosen the object to the rotary base; and turning the second part by said other portion so that the rotary base, the bolt and the first part remain free of rotation to urge the bolt in the desired axial direction to tighten or loosen the object to the rotary base.
The advantage of the proposed method is that the bolt remains free of torsion, no additional holding tool is required, no adjacent stationary object is required, there will be no side load applied to the bolt as a result of abutting a holding tool against the stationary object, the job becomes safer, the setup is simpler, and the work gets done faster.
The novel features which are considered as characteristic for the present invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.